The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent the work is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
When operating in an infrastructure mode, Wireless Local Area Networks (WLANs) typically include an access point (AP) and one or more client stations. Development of WLAN standards such as IEEE §§802.11a/b/g/n has focused primarily on improving single-user peak data throughput. For example, IEEE §802.11b operate at a single-user peak throughput of 11 Mbps, IEEE §802.11a/g operates at a single-user peak throughput of 54 Mbps, and IEEE §§802.11n operates at a single-user peak throughput of 600 Mbps.
In these WLANs, the AP transmits information to one client station at a time in a unicast mode. Alternatively, the same information may be transmitted to a group of client stations concurrently in a multicast mode. This approach reduces network efficiency because other client stations need to wait until the current client station or group of client stations is serviced. When transmitting the same information to the group of client stations, throughput may be limited by one of the client stations with the weakest reception.
For uplinks, the client stations typically contend for access to the medium. In other words, only one client station may transmit uplink data to the AP at a time. For example, the client stations may contend for the channel using Carrier Sense Multiple Access (CSMA). One client station may transmit when there are no other client stations transmitting. When a client station detects activity, the client station waits a random backoff period before retrying. This approach is inefficient for several reasons. Uplink transmission cannot be guaranteed to occur within a particular time frame. In addition, inefficiency tends to increase as the number of client stations increases.